Not all Shopping ads are equal. This example shows how Comparison Shopping Services varies and it matters more than you think.

When Comparison Shopping Services (CSS) launched across Europe, many brands made the switch to a third-party CSS to benefit from one major incentive: lower CPCs.

The mechanism was simple.

Under EU antitrust regulation, Google had to open up Shopping placements to competitors. To level the playing field, those competitors (i.e. CSS partners) could place bids with up to a 20% advantage over Google Shopping. For brands, this translated into cheaper clicks and more exposure.

But post-Brexit, the game has changed.

What Changed for the UK?

That ~20% edge? Gone.

And yet, many UK-only brands continue using CSS by default, without reassessing if it’s still the right fit.

If you’re selling to EEA or Swiss markets, the discount still applies. So for international retailers, CSS can absolutely remain valuable. But for UK-only advertisers, continuing with a CSS provider might mean you’re paying for a service that no longer gives you the intended advantage.

For brands or agencies currently switching from Google Shopping CSS or searching for the best Google Shopping CSS partners, it’s worth re-evaluating whether those Comparison Shopping Service providers are still delivering value for your UK activity.

Do Consumers Trust Alternative Comparison Shopping Services?

Another factor to consider is how consumers perceive Shopping ads. Many third-party CSS ads carry a label like “by ShopXYZ” instead of “by Google,” and this branding does not go unnoticed.

In discussions across PPC communities, advertisers have raised concerns about unfamiliar CSS labels impacting trust. One advertiser on Reddit asked:

“I feel like using another CSS provider like Producthero will affect customers’ trust because it doesn’t say ‘by Google’, is this correct?” (source)

While there is no definitive CSS-specific study on this yet, broader research supports the idea that platform trust matters.

A 2023 study in Humanities & Social Sciences Communications found that users are more likely to complete a purchase from a platform they recognise and trust, even if the price is higher (Nature.com).

Put simply, ads marked “by Google” may benefit from greater shopper confidence.

What We Recommend: Split-Test Your CSS

We believe data should drive decisions. That’s why we recommend UK brands to run a controlled split test:

  • One Shopping campaign via Google CSS (i.e., default Google Shopping)
  • One Shopping campaign via your existing third-party CSS

Track and compare:

  • Cost-per-click (CPC)
  • Click-through rate (CTR)
  • Conversion rate
  • Return on ad spend (ROAS)

We’ve run tests with our clients, and after finding better performance and engagement chose to switch back to Google. In other cases, CSS still holds value, particularly if the provider delivers cross-market capabilities, support and reporting capabilities.

If you’re currently searching through a Comparison Shopping Service providers list, or wondering which setup suits your business best, real test data will beat guesswork every time.

Reassess Your Comparison Shopping Services, Don’t Remove

We’re not saying CSS is dead. But for UK-only brands, the time of set-and-forget is over. The landscape has shifted, and the only way to be certain you’re making the most of your Shopping investment is to review your setup.

Does your CSS partner still give you a competitive edge? Or are you better off simplifying and returning to Google?

Not sure if your CSS setup is helping or hurting?

Book a free Google Shopping feed audit with our team and get clarity before peak season hits.

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